Studies on a Novel Qualification Method of Silicon Nitride Layer Available to Purchase

In wafer fabrication, a silicon nitride (Si3N4) layer is widely used as passivation layer. To qualify the passivation layers, traditionally chemical recipe PAE (H3PO4+ HNO3) is used to conduct passivation pinhole test. However, it is very challenging for us to identify any pinholes in the Si3N4 layer with different layers underneath. For example, in this study, the wafer surface is Si3N4 layer and the underneath layer is silicon substrate. The traditional receipt of PAE cannot be used for passivation qualification. In this paper, we will report a new recipe using KOH solution to identify the pinhole in the Si3N4 passivation layer.